Hydraulic operating mechanism



June `1, 1.937.` G. w. BowER HYDRAULIC OPERATING MECHANISM 'Filed Aug.3, 1934 Firgl.

Invent oT` George W. Bowen torneg.

J equallzing means arranged to prevent leakage of Patented June l, 19.37

UNITED STATES 2.082.613 HYDRAULIC OPERATING MECHANISM George W. Bower,'Wesleyville, Pa., .assignor to General Electric Companna corporation'of New York Application August 3,1924; Serial No. '138,242'V sanimalier. en -52) My invention relates to hydraulic operatingmechanisms of the type provided with `a piston and has for an object theprovision of pressure the operating iiuid from the mechanism.

Heretofore hydraulic operators of the type shown in patent applicationSerial No. 708,637, McNairy, tiled January 27, 1934, now PatentV No.11,072,481,v issued March 2, 1937, entitled Hy- '1 draulic operatingmechanism for circuit breakers and the like, and assigned tothe sameassignee as the present invention, have been used to reset circuitbreakers, After the hydraulic operator has closed or reset the circuitbreaker, a large valve opens permitting the'quick return of theoperating piston. A pressure greater than atmosf pheric pressure isthereby generated in the cylinder causing leakage oi? a mixtureoffentrapped air and oil around the piston and the pump shaft. I

In carrying out my invention in one form thereof, I provide anattachment for equalizing the pressure within the cylinder with theatmospheric pressure outside of the cylinder. More specifically, Iprovide an auxiliary oil chamber and an automatically operated valve forventing the cylinder through the chamber to thel outside atmospherewhile separating the leakage oil from the mixture of oil andair andreturning the oil to the cylinder.

For a more complete understanding of my invention, reference should nowbe had to the drawing wherein I have shown in Fig. 1 a sectionalelevation of my invention applied to a hydraulic operator; Fig. 2 is anenlarged sectional elevation of an attachment embodying my invention;Fig. 3

isa fractional sectional elevation taken on the lines 3-3 of Fig. '1,while Fig. i'illustrates diagrammatically the hydraulic operator with my/attachment applied to it. l

Referring to the drawing, I have shown my invention in one. form asapplied to a hydraulic operator It `provided with acylinder II within`which is slidably moimted a piston I2 connected by piston rod I4 to anactuating plate I5 located on the outside of the cylinder. A coil springI6 strongly biases the piston to one position, the

piston being operable upwardly against the bias of the spring I6 bymeans of a pressure producing device shown as a gear pump I3. The gearpump is driven byan electric motor (not shown) conthe upper face I2a. ofth'e piston I2 against the face v25'of a bypass valve'26. As thepressure builds up against the bypass valve 26 it is operated againstthe bias Vof a spring 2l to close a bypass 'channel 28 extending onopposite sides of the directly to that part of the cylinder locatedbelow the face 12b of the piston I2. As' the hydraulic pressure isincreased by the gear pump the piston I2 is operated against the bias ofits spring I8 upwardly, the actuating plate I5 being moved thereby intoengagement with a switch actuating member 32, which member can be usedto reclose a circuit breaker or' for any other purpose. As soon as thepiston. reaches apredetermned second position, the rotation of the shaft20 is interrupted by the deenergizatlon of its driving motor. The motorcan be deenergized either by a limit switch or by a manually operableswitch. neither being shown in the drawing. As soon as the gears 22. and23 are brought tol a standstill the pressure against the lower face I 2bof the piston immediately drops to zero. 'I'he spring 21 thereuponquickly accelerates the valve 26 to the position shown in Flg. 1,opening the bypass A channel 28. At the same time, the spring I6 actingagainst the upper face I2'a of the piston imma-,

, diately accelerates the piston towards itsoriginal position.

oil from below the piston I2 rushes through the bypass channel 28 to theupper side of the piston. 'I'he resulting turbulence and the stirringcauses the oil to foam and to ll the space adjacent the upper end of thecylinder with a iiuid mixture of oil and air. Since the pistonrod movinginto the cylinder occupies a substantial proportion of the volume withinthe upper portion of the cylinder, the foam or fluid mixture of oil andair is subjected to a pressure. This pressure is produced because for agiven transfer of oil from the'lower to the upper side of the piston duetoyrovement of the piston, the increase of volume above the piston isless than the decrease in the volume below the piston. Thedifferencefbetween the two volumes-the volume of the .additional portionof the piston rod introduced into the cylinderbeing taken up by thecompressionoi the iluid mixture.

Heretofore the pressure was released by the flow of the fluid mixturearound the piston rod Id through its guide, bearing A36 to theatmosphere.

VThis iiow has not only been undesirable but has made necessary periodicreplenishment of the I5 `-oil supply within the cylinder. There was alsosome leakagel oil which escaped'through the housing 31 provided aroundthe pump actuating shaft 2'0.

In accordance with my invention pressure in the upper portion of thecylinder is immediately relievedthrough an inlet opening 40 located onthe upper end 42 of the cylinder Il and permitting a flow of the uidmixture of air and oil from the cylinder into' a container mounted onthe cylinder'by screw-threaded engagement of its lower end 45 with thecylinder. A valve 46 mounted adjacent the inlet opening 40 is guided formovement between predetermined positions by a valve stem 41 whichslidably engages the walls of the passageway 48 extending betweenopposite ends of the container 44; An opening 43 connects the passageway48 to the upperend 56 of the container while aplurality ofaperturesconnect the lower end 52 of the container to a passageway 53 of largerdiameter than the valve stem 41 so that oil can iiow through thispassageway 53 from the container to the cylinder,

, openings 54 being provided in the valve 46 to per- 'perm1ts the freenow or uuid in the farm of ou 40 to the cylinder Ii.

mit. the return of the oil around the (valve.

- Whenv pressure exists within-l the upper portion ofthe cylinder,however, the valve46 vis actuated upwardly from thevposition shown to asecond position in which the valve 46 seats against the surface 56 andthereby closes the passageway 53.

A ductforpajssageway 53 provided through the central -portion of thevalve 46 and its stem 41 ioamirom the cylinder through the passageway 48and theopening 49 to the container 44. The sharp right-angle turnprovided bythe opening 49 between the passageway 43 and the upper end 50of the chamber abruptly changes the direct tion of'travel of the iluidsc that the liquid oil collects on the bottom of the container while theair is exhaustedtoatmosphere throughv an outlet 60 formingl a vent atatmospheric pressure.

I have found that bythe time the uid mixture `reaches the lowerportiono! the container the liquid and gaseous portions haveso farseparated that Ano perceptible quantity of liquid is carried to theatmosphere.

As soon as the pressure within the cylinder is relieved, thel valve 46operates by gravity to its firsty position, permitting the return ilowof the oil which has been trapped in the container 44 to iiow throughthe apertures 5i, the passageway 53, and around the openings 54 throughthe inlet Since the duct 56 is relatively large as compared with theopening around the piston rod I4 and the opening around the drivingshaft 20. I have found that the pressure in the `upper portion of thecylinder is diminished so rapidly that no leakage occurs around eitherthe piston or the driving shaft. Consequently, the annoyance of leakageis entirely eliminated by my pressure equalizer and no liquid lossesoccur since all of the liquid is returned to the cylinder.

said piston, comprising a container provided with inlet and outletpasageways, said inlet passageway connecting the container to theopposite side of said piston and said outlet passageway forming a ventat atmospheric pressure for said container, a connecting passageway,i'ormed so as to change abruptly the direction of ow between said inletand outlet passageways and thereby permit the escape oi gas butpreventing escape of said fluid from said container, and a pressureoperated valve in said inlet passageway normally permitting a returnilow of liquid from Baidjcontainer and operable in response to pressatmospheric pressure ior preventing `the return now of liquid from' saidcontainer, said valve including means for connecting at all times saidinlet passageway and said connecting passage- Way.

2. Pressure f equalizing means comprising 'a casing provided with aninlet and a .vent to the atmosphere, normally open valve meansconnecting said inlet4 with said casing, said valve means having apassageway at all times connecting said inlet with a remote portion cisaid casing, and means within said casing forming a restricted flow pathfrom said passageway for changing abruptly the direction of said flowpath, said normally open valve means being movable to a closed positionin response-to the pressure at said inlet to restrict to said passagewaythe flow path from said inlet to said casing.

3. Pressure equalizing means for hydraulic operators provided with acylinder and pistonl mounted therein, comprising a container, wallsforming a passageway extending substantially between the ends ofI saidcontainer and open at opposite ends of said container, an inlet betweenone end c! said container and said cylinder, a valve slidably mounted insaid passageway operable between predetermined positions for opening andclosing said inlet, said valve having -a duct providing at all times ailow path from said cylinder to said passageway, said container beingprovided with `an outlet remotely located from said inlet and opening tothe atmosphere.

4. Pressure equalizing means for hydraulic 0perators provided with acylinder and a piston comprising an'oil-receiving container, an inletfrom said cylinder to" one end of said container,

walls forming a passageway from said inlet to the opposite end of saidcontainer, said opposite end o`f said container being provided with anoutlet opening to the atmosphere, a valve guided by said passageway foroperation between predetermined positions, said valve being providledwith a conduit for connecting at all times said container to saidpassageway, said valve being operable by pressure within said cylinderfor closing said inlet to restrict ilow of iluid iron' said cylinder tosaid container through said passageway.

5. Pressure equalizing means for preventing the ilow of leakage liquidfrom a hydraulic operator provided'with a cylinder, a piston, and

a. piston rod extending through the walls of said cylinder comprising, acontainer provided with a passageway open at opposite ends of saidcontainer, an inlet connecting both said container and its passageway tosaid cylinder, a valve operable by pressure in said cylinder from oneposition to a second position for connecting said' inlet to saidpassageway only, and when in said ilrst position connecting said inletto both said passageway andsaid container. whereby pressure within "saidc'ylindeiis quickly exhaustedzto aosaers 3 said casing, means withinsaid casing i'orminga restricted iiow path from said passageway forchanging abruptly the direction oi said ow "path, and an additionalpassageway normally connecting said casing to said inlet, said valvebeing operable to close said additional passageway and restrict therebysaid iiow path tosaid passageway provided ln said valve means.

GEORGE W. BOWER.

